Charles J. Lada

Conceived in the mysterious process that transforms diffuse
interstellar matter into massive and dense molecular cloud cores,
embedded stellar clusters account for a significant fraction of all
star formation currently occurring in the Galaxy. Consequently many of
the fundamental properties of the Galactic stellar population are
forged in such clusters and such properties form the critical boundary
conditions for the development of a theory for star formation. In the
first part of this lecture I will discuss the current status of our
knowledge of embedded clusters including such issues as their ages and
lifetimes, the cluster mass function, and their early dynamical
evolution and origin in molecular clouds. In the second part of this
lecture I will review the current knowledge concerning stellar
multiplicity and the functional form and universality of the stellar
IMF. The stellar IMF is one of the most fundamental distributions in
astrophysics and the key boundary condition any theory of star
formation must satisfy. Detailed knowledge of the functional form of
the IMF and how this quantity varies through space and time is
necessary to predict the evolution of all stellar systems from star
clusters to galaxies. I will discuss how infrared observations of
young embedded clusters have enabled the extension of the IMF well into
the substellar mass regime, provided insights concerning its
universality, and revealed the existence of a characteristic mass for
star formation. Finally, I will briefly discuss recent observations of
stellar multiplicity that indicate that, contrary to long held
opinions, most star systems in the Galaxy consist of single stars.